Three in 10 Windows PCs still vulnerable to Conficker exploit

Three in ten systems remained unpatched against the exploit fueling the spread of the infamous Conficker worm, according to security tools firm Qualys.

Conficker, aka Downadup, which began circulating in late November, exploits the MS08-067 vulnerability patched by Microsoft last October. The worm also spreads over network shares. Security watchers reckons the worm has clocked up more than nine million victims, based on an analysis of how infected machines attempt to contact a changing network of pre-programmed domains.

The worm has been able to build the largest botnet on record largely because sys admins have been slow to cut down the vulnerability responsible for fueling its spread. Based on vulnerability scans of several hundred thousand Windows PCs, Qualys said about 30 per cent of computers are yet to apply a out-of-sequence patch Microsoft released in late October. The patch was a response to Trojan attacks already in circulation against a security bug in Windows Server service.

"The unpatched numbers went down significantly around the 30-day mark," said Wolfgang Kandek, Qualys' chief technology officer, "when less than 50 per cent were unpatched. After that, it went down a little slower. As of yesterday, 30 per cent of the machines are unpatched."

Kandek, whose firm sells vulnerability scanning services, reckoned slow-vulnerability patching cycles in enterprise users are leading to the prolific spread of the worm. The worm is not the work of a malware coding mastermind.

Security researchers at McAfee have discovered that the malicious code makes use of exploit code from Metasploit, the open-source penetration testing tool. "By using the exploit from the Metasploit module as the code base, a virus/worm programmer only needs to implement functions for automatic downloading and spreading," according to Xiao Chen, a McAfee security researcher in a blog posting.

In response to widespread attacks, Microsoft added routines to clean up Conficker infections to the January edition of its Malicious Software Removal Tool. ®